What's new
By:
Filters

Steering Reservoir Tech (and Demo)

RadialDynamics

RadialDynamics

Yellow Skull
Joined
Dec 22, 2020
Member Number
3165
Messages
156
Loc
Greenfield, MA USA
Time to take a good look at steering reservoirs. If you think about it, how many people seem to have trouble with their off-road steering pumps? Pumps marketed for hydro assist and full hydro off-road applications typically have their valving increased in both pressure and flow from OEM applications which stresses the steering system and makes the pump all the more sensitive to wear and failure due to inadequate system design.

The reservoir is THE component that feeds the pump so of all the parts that make up a steering system, the reservoir is what has the greatest influence over the pump performance and reliability but at the same time, it is typically the least considered, brushed off as an afterthought. The Vortex Reservoir design is what I came up with to help the Big B Motorsports Ultra4 team back in 2017-2018 when they were struggling to keep their high flow pumps alive and it is this design that was solely responsible for the launch of Radial Dynamics.

This demo is the first time I have ever revealed the entirety of what happens inside of the Vortex Reservoir. If you struggle with steering pump reliability and often find foamy fluid, I guarantee this is well worth the watch.

 
Last edited:
Might want to fix the typo on the vid....
 
Awesome setup, If i run my system with standard reservoir and have no issue or foaming yours isn't necessary?

Another thing if you run your remote oil filter you can run 2 in and 1 out from a hydroboost and steeering box which allows a standard 1 return and 1 fee PS reservoir? Thanks
 
Last edited:
It's a cool idea but how bout just eliminating the cavitation to start with? Not trying to be a dick, I'm just asking. Seems like guys might be running too small of a feed line on their high flow pumps?
 
That is a great display as really shows the removal of bubbles. Something people can see working in action. No doubt this would be useful on start up to purge the system of entrapped air.
Aeration ≠ Cavitation
Aeration is when the hand valve was opened and air was entered into the pump stream which worked its way to the reservoir where it could float its way to the top.
Cavitation is when a low pressure area is created and vapor bubbles are created. When the vapor bubbles are no longer in a low pressure area they collapse as they are not air and will not accumulate like air. So Aeration and Cavitation are two very different things.
The centrifugal effect of the reservoir created its own high and low pressure area creating cavitation not from the pump but from the velocity of the fluid in the reservoir. The vapor bubbles stayed visible as they worked their way up through the low pressure path in the reservoir until they reached the upper section of the reservoir where the pressures equalized and they collapsed, they did not join the air as aerated bubbles would.
While the reservoir appeared to work well at lower 5 GPM by de-aerating and not cavitating, it was not able to flow at the 15 GPM level without cavitating. This was not the pump cavitating, but the centrifugal action cavitating.
It other words it creates and solves it own problems when running at the higher flow rates.
I am still not convinced that centrifugal reservoirs are necessary compared to a properly bled system. If the system is bled properly and air is separated from the flow path by use of baffles or plumbing or an overflow then there is no air to keep separating.
Aviation reservoirs are sealed units purged of air that act like accumulators and this has been proven to work in the most demanding applications. This is also how I ran my last buggy.
I do believe the centrifugal separators have a place for those who do not want to bleed their systems properly or can not, due to the way the the system has been plumbed or components mounted.
I am interested to see the demo system running with actual oil as the viscosity will be different.
As with many cyclonic and centrifugal separators in different industries, they have a flow range. Too slow and they do not work, too fast and they will restrict flow or cavitate.
 
I don't really have any problems with my current setup but I've wondered for a long time about a reservoir with a dividing piston pressurized on the top side like a shock.
 
HYDRODYNAMIC said:
As with many cyclonic and centrifugal separators in different industries, they have a flow range. Too slow and they do not work, too fast and they will restrict flow or cavitate.
Click to expand...

Didn't you run an airbag for a reservoir/expansion tank on the last buggy?
 
Awesome setup, If i run my system with standard reservoir and have no issue or foaming yours isn't necessary?

Another thing if you run your remote oil filter you can run 2 in and 1 out from a hydroboost and steeering box which allows a standard 1 return and 1 fee PS reservoir? Thanks
Click to expand...
I won't say it's unnecessary... it will still provide value even if foaming isn't a problem with your current setup such as the 100% circulation and pump feed at extreme angles. If you also are the type of driver that finds yourself rolling over regularly then there is the obvious benefit of quickly eliminating any air that might get ingested into the system when upside down. It's a matter of how you use your vehicle that influences how valuable it will be to you.

To answer your second question, yes, I use remote filters with two inlets to run a hydroboost or external pressure relief valve return. The benefit to doing this with an external pressure relief, especially, is that the relief valve produces the hottest oil in the system so running it to a remote filter allows you to place your cooler between that and the reservoir, thereby cooling 100% of your flow including the hottest oil in the system.


It's a cool idea but how bout just eliminating the cavitation to start with? Not trying to be a dick, I'm just asking. Seems like guys might be running too small of a feed line on their high flow pumps?
Click to expand...
Truth is, every system will cavitate to an extent. Even with proper hose sizing/routing and pressure in the reservoir, there will be some amount of cavitation at high RPM due to the physical challenge of getting fluid into a cavity at such high speed. Oil is also prone to hold dissolved air, up to 10% by volume. Air molecules fill in the voids between oil molecules and it takes very little reduction in pressure to cause air to come out of solution and form bubbles so even with a system that has been properly and thoroughly bled, bubbles can still appear. But yes, the goal is to eliminate causes of cavitation and aeration to the extent that the reservoir has to do as little de-aerating as possible.

Aeration ≠ Cavitation
Aeration is when the hand valve was opened and air was entered into the pump stream which worked its way to the reservoir where it could float its way to the top.
Cavitation is when a low pressure area is created and vapor bubbles are created. When the vapor bubbles are no longer in a low pressure area they collapse as they are not air and will not accumulate like air. So Aeration and Cavitation are two very different things.
The centrifugal effect of the reservoir created its own high and low pressure area creating cavitation not from the pump but from the velocity of the fluid in the reservoir. The vapor bubbles stayed visible as they worked their way up through the low pressure path in the reservoir until they reached the upper section of the reservoir where the pressures equalized and they collapsed, they did not join the air as aerated bubbles would.
While the reservoir appeared to work well at lower 5 GPM by de-aerating and not cavitating, it was not able to flow at the 15 GPM level without cavitating. This was not the pump cavitating, but the centrifugal action cavitating.
It other words it creates and solves it own problems when running at the higher flow rates.
I am still not convinced that centrifugal reservoirs are necessary compared to a properly bled system. If the system is bled properly and air is separated from the flow path by use of baffles or plumbing or an overflow then there is no air to keep separating.
Aviation reservoirs are sealed units purged of air that act like accumulators and this has been proven to work in the most demanding applications. This is also how I ran my last buggy.
I do believe the centrifugal separators have a place for those who do not want to bleed their systems properly or can not, due to the way the the system has been plumbed or components mounted.
I am interested to see the demo system running with actual oil as the viscosity will be different.
As with many cyclonic and centrifugal separators in different industries, they have a flow range. Too slow and they do not work, too fast and they will restrict flow or cavitate.
Click to expand...

Absolutely correct about the difference between aeration and cavitation. They are not the same. Both are shown in the video, the initial clouding of the center chamber is due to cavitation (and probably a little aeration from leaking fittings) and the opening of the air intake valve is most definitely causing aeration. I can assure you though that the clouding that occurred at 15 GPM was caused by the pump, not the reservoir itself.

I have a flow meter on this setup with a standard globe valve to modulate flow and as soon as this particular pump in this particular setup hit 12 GPM, a tone change from cavitation occurs in the pump which is when the bubbles start to appear. If they were strictly the result of cavitation due to low pressure in the mid-reservoir inlet chamber, then that would imply that the center of that chamber is below atmospheric pressure. This video proves that the center of the mid chamber is above atmospheric pressure by the very fact that flow is forced from there to the lower-pressure (and definitely atmospheric) top chamber, both with and without air (if you pay close attention to the water surface when not cavitating) and when in vertical and horizontal orientations. By that evidence, I am relying on higher pressure in the mid chamber and not just buoyancy of collected gas bubbles to induce flow through the smaller vertical tubes.

I did perform the following partial cutaway demo with steering fluid almost two years ago (back when I was a little more awkward on camera). The effect is the same:


And don't worry, I have a reservoir with spin on filter here that will also be getting cut apart for a similar demo pretty soon.
 
Very cool on how it work.

I don’t see anything on your website on its serviceability. Look like it can be difficult to clean out contaminated oil or debris as if something failed within the system.
 
TrailTamer said:
Very cool on how it work.

I don’t see anything on your website on its serviceability. Look like it can be difficult to clean out contaminated oil or debris as if something failed within the system.
Click to expand...

It would be difficult to physically scrub all the internal surfaces but all of these reservoirs do feature a magnetic drain plug so you can drain and flush contaminated fluid.
 
Cool, I like clear view stuff. The parts geek in me has a laundry list of things I want to make clear ones of just to look inside while they work.
 
TrailTamer said:
Very cool on how it work.

I don’t see anything on your website on its serviceability. Look like it can be difficult to clean out contaminated oil or debris as if something failed within the system.
Click to expand...

adding the spin on filter to the system will do the majority of the work for catching system failure
 
RadialDynamics said:
I can assure you though that the clouding that occurred at 15 GPM was caused by the pump, not the reservoir itself.

If they were strictly the result of cavitation due to low pressure in the mid-reservoir inlet chamber, then that would imply that the center of that chamber is below atmospheric pressure. This video proves that the center of the mid chamber is above atmospheric pressure by the very fact that flow is forced from there to the lower-pressure (and definitely atmospheric) top chamber
Click to expand...

If the water was still then your statement would be true. When the water is spinning with force it is creating a concentrated low pressure area even if the surrounding area is at atmospheric pressure. Whether it is a pump blade or a sharp 90* fitting or a centrifugal force or a change in velocity, a high and low pressure area is being created as the water can not move fast enough to equalize.
This can be seen in a simple Venturi. No moving parts only the flow of the liquid and change of velocity creating cavitation. This is what I believe is happening inside the reservoir. The severity of the cavitation depends on how much air is in the oil. Rather than have to pull a vacuum with completely de-aerated water, a little air bubble can be increased in size. Through the video you can see the cavitation effect based on how de-aerated the incoming liquid is.



 
Last edited:
HYDRODYNAMIC said:
If the water was still then your statement would be true. When the water is spinning with force it is creating a concentrated low pressure area even if the surrounding area is at atmospheric pressure. Whether it is a pump blade or a sharp 90* fitting or a centrifugal force or a change in velocity, a high and low pressure area is being created as the water can not move fast enough to equalize.
This can be seen in a simple Venturi. No moving parts only the flow of the liquid and change of velocity creating cavitation. This is what I believe is happening inside the reservoir. The severity of the cavitation depends on how much air is in the oil. Rather than have to pull a vacuum with completely de-aerated water, a little air bubble can be increased in size. Through the video you can see the cavitation effect based on how de-aerated the incoming liquid is.

https://www.youtube.com/watch?v=SeVW6GUqy6U

https://www.youtube.com/watch?v=xBqSEgaaFdM
Click to expand...

Embedded:

 
Watch those venturi vids and then take a look at your pump outlet. Mine's drilled out to 11/64's. I might even go 3/16's in the future. I don't know if it helps but it's probably not hurting.
 
DesertCJ said:
Watch those venturi vids and then take a look at your pump outlet. Mine's drilled out to 11/64's. I might even go 3/16's in the future. I don't know if it helps but it's probably not hurting.
Click to expand...

it might hurt, check out the "cbr" thread from agitated pancake. the outlet restriction helps size the output flow vs the recycled flow balance and if you start pushing too much volume out rather than recycled, you make it easier to starve/cavitate your pump and can push up your line speeds pretty high if you don't increase those through the system as well.

advantage of a de-aeration reservoir for offroad use aside from initial startup is that it will continue to function even if you hit angles and increase your chance of getting bubbles in the system from that abuse.
 
RadialDynamics said:
I won't say it's unnecessary... it will still provide value even if foaming isn't a problem with your current setup such as the 100% circulation and pump feed at extreme angles. If you also are the type of driver that finds yourself rolling over regularly then there is the obvious benefit of quickly eliminating any air that might get ingested into the system when upside down.
Click to expand...

That's a pretty big deal !

Thanks for sharing tech on your resi !
 
RadialDynamics said:
Truth is, every system will cavitate to an extent. Even with proper hose sizing/routing and pressure in the reservoir, there will be some amount of cavitation at high RPM due to the physical challenge of getting fluid into a cavity at such high speed. Oil is also prone to hold dissolved air, up to 10% by volume. Air molecules fill in the voids between oil molecules and it takes very little reduction in pressure to cause air to come out of solution and form bubbles so even with a system that has been properly and thoroughly bled, bubbles can still appear. But yes, the goal is to eliminate causes of cavitation and aeration to the extent that the reservoir has to do as little de-aerating as possible.
Click to expand...

I think it was Bilstein, years ago, probably at SEMA, had a clear shock absorber, with a cycling pressure charge that went probably 0-200 and back over the span of a minute or so, and the shock stroked back and forth. You could watch as the pressure got lower, the shock piston cavitating its way through the oil, and as the pressure was increased, the bubbles magically disappearing and the shock actually working. Really neat demo item.

With recreational offroad being what it is, I think some air in the PS fluid is just a "deal with it" thing. We don't have the budget, the space, or the parts tech, to put a nitrogen charged accumulator equipped air purged system together that would eliminate it entirely, so we make-do with reservoirs that get rid of what air does end up in the fluid stream, as quickly as possible. I wanted a while back to do a floating piston reservoir to address this, but couldn't build what I wanted; I ended up with a plum-full primary reservoir and a surge tank to get what I'd call 95% there. For me, that worked well enough that I've been using a variant of that ever since. The surge tank has since proven its value for me since I use my system as auxiliary PTO hydraulics (log splitter, jackhammer, similar silliness) and not all of that is balanced-cylinder type of flows. I see a few different things going on in this one, and a couple bits I can't seem to make out from the video what's going on (most clearly "I can see what I can't see" when you tip it on its side), some drysump swirl tank stuff, some of what I used when I built my current reservoir, looks like a nice setup to get to good/fast air separation for when it invariably does happen.
 
ScottRS said:
I think it was Bilstein, years ago, probably at SEMA, had a clear shock absorber, with a cycling pressure charge that went probably 0-200 and back over the span of a minute or so, and the shock stroked back and forth. You could watch as the pressure got lower, the shock piston cavitating its way through the oil, and as the pressure was increased, the bubbles magically disappearing and the shock actually working. Really neat demo item.

With recreational offroad being what it is, I think some air in the PS fluid is just a "deal with it" thing. We don't have the budget, the space, or the parts tech, to put a nitrogen charged accumulator equipped air purged system together that would eliminate it entirely, so we make-do with reservoirs that get rid of what air does end up in the fluid stream, as quickly as possible. I wanted a while back to do a floating piston reservoir to address this, but couldn't build what I wanted; I ended up with a plum-full primary reservoir and a surge tank to get what I'd call 95% there. For me, that worked well enough that I've been using a variant of that ever since. The surge tank has since proven its value for me since I use my system as auxiliary PTO hydraulics (log splitter, jackhammer, similar silliness) and not all of that is balanced-cylinder type of flows. I see a few different things going on in this one, and a couple bits I can't seem to make out from the video what's going on (most clearly "I can see what I can't see" when you tip it on its side), some drysump swirl tank stuff, some of what I used when I built my current reservoir, looks like a nice setup to get to good/fast air separation for when it invariably does happen.
Click to expand...

I don't think it would be too hard to build a reservoir with a dividing piston? Put a bleed screw in it to get the initial air out the way we do shocks and then put a Schrader in the rezzy cap. What I don't know is how the system is going to like returning oil into a rezzy under pressure? Or what would happen if you do get cavitation/air in the oil behind the piston? Will it dissolve back into the oil or develop a large air gap between the oil and the piston? Or what pressure if any would be beneficial? Lots of questions with possibly no benefits but it's an interesting idea...
 
ScottRS said:
With recreational offroad being what it is,
Click to expand...

if you check out the website and look at the prices ($845 for a 4" reservoir :eek:) i dont think the OP is going to have much luck with recreational offroaders buying his product
 
DesertCJ said:
Watch those venturi vids and then take a look at your pump outlet. Mine's drilled out to 11/64's. I might even go 3/16's in the future. I don't know if it helps but it's probably not hurting.
Click to expand...

That outlet you are talking about is tuning the bypass valve. There are consequences to drilling it out. Have a look at the CBR thread as mentioned.

qGhiEIe.gif
 
DesertCJ said:
I don't think it would be too hard to build a reservoir with a dividing piston? Put a bleed screw in it to get the initial air out the way we do shocks and then put a Schrader in the rezzy cap. What I don't know is how the system is going to like returning oil into a rezzy under pressure? Or what would happen if you do get cavitation/air in the oil behind the piston? Will it dissolve back into the oil or develop a large air gap between the oil and the piston? Or what pressure if any would be beneficial? Lots of questions with possibly no benefits but it's an interesting idea...
Click to expand...

Whole lot of I don't know there, honestly. The Bilstein demo item didn't really seem to get much benefit in the 0-100psi range IIRC, it was over 100psi where it started to matter. I don't know what happens if you pressurize PS stuff past 100psi (or even to 100psi), the farthest I've personally gone is radiator-cap-level pressure.

If there's a leak in the system, topping it up is another chore, lose a line, you can't typically trail-fix that any more. Building the reservoir, you're building an accumulator... it gets complicated fast. Initial bleed/purge is a pain, but once it's done, as long as there's no issues, it should be good for a long time, but if it's less-than-perfect, you've trapped the suck in with it too.
 
ScottRS said:
With recreational offroad being what it is, I think some air in the PS fluid is just a "deal with it" thing. We don't have the budget, the space, or the parts tech, to put a nitrogen charged accumulator equipped air purged system together that would eliminate it entirely, so we make-do with reservoirs that get rid of what air does end up in the fluid stream, as quickly as possible. I wanted a while back to do a floating piston reservoir to address this, but couldn't build what I wanted; I ended up with a plum-full primary reservoir and a surge tank to get what I'd call 95% there. For me, that worked well enough that I've been using a variant of that ever since. The surge tank has since proven its value for me since I use my system as auxiliary PTO hydraulics (log splitter, jackhammer, similar silliness) and not all of that is balanced-cylinder type of flows. I see a few different things going on in this one, and a couple bits I can't seem to make out from the video what's going on (most clearly "I can see what I can't see" when you tip it on its side), some drysump swirl tank stuff, some of what I used when I built my current reservoir, looks like a nice setup to get to good/fast air separation for when it invariably does happen.
Click to expand...

I had a hard time not just putting the Variable Volume Reservoir from the old buggy onto the new one. I fought with myself to go mainstream and use what everyone else is using and make it work best I could.
If you want to nerd out check out SeaTools, they make deep sea compensators which are variable volume reservoirs with a 20 year service life at the bottom of the sea floor 16,404 feet below the surface. They even make a cute little one with .21 gal capacity.
https://www.seatools.com/wp-content/uploads/2016/12/Ultralong-Lifetime-Compensator-0.7L-v1.pdf
 
rockyota83 said:
if you check out the website and look at the prices ($845 for a 4" reservoir :eek:) i dont think the OP is going to have much luck with recreational offroaders buying his product
Click to expand...

Perhaps not. I don't know, and I'm probably not a great example; I've never paid enough to get into three digits for a reservoir. But the last one I built, I have several hours worth of my time, and probably $100-150 in bits, in making it, and it's nowhere near as pretty as his; if I billed my time at shop rate, I'd be easily into $6-something hundred bucks (and still ugly). I can't use his (I need dual outlets) anyway, so kind of a moot point to me, but if his works in practice as well as the clear mockup does in the video, I don't think it's out of the realm of the mid-to-higher-spend (buggy/tubecar/race/whatever) guys at all. I don't think anybody's buying this to slap on their TJ on 35's to go overlanding. I do like that he's willing to show and talk about (at least a good bit of) the tech bits in there, 'cause guys like me will poach tech and put it in our lowbuck DIY junk too. That's why there are pictures of what's in mine in my build thread, I'm a tech geek who likes to see stuff that works (and learn from stuff that doesn't).
 
HYDRODYNAMIC said:
I had a hard time not just putting the Variable Volume Reservoir from the old buggy onto the new one. I fought with myself to go mainstream and use what everyone else is using and make it work best I could.
If you want to nerd out check out SeaTools, they make deep sea compensators which are variable volume reservoirs with a 20 year service life at the bottom of the sea floor 16,404 feet below the surface. They even make a cute little one with .21 gal capacity.
https://www.seatools.com/wp-content/uploads/2016/12/Ultralong-Lifetime-Compensator-0.7L-v1.pdf
Click to expand...

That's pimp, my inner nerd thanks you for the diversion! :beer:

A little (OK, probably a lot, like in the "I didn't even try to look it up" realm) out of my wheelhouse cost-wise, I'm sure, but still cool tech.
 
You must log in or register to reply here.
Top Back Refresh